A variety of implantable infusion devices are available for treating patients. For example, implantable infusion devices are used for delivering therapeutic substances to a target location of a patient. The implantable infusion devices are typically implanted subcutaneously in a convenient location in the patient. An infusion catheter is typically connected to an outlet of the device and positioned in the patient to allow delivery to the target location. A therapeutic substance is then typically introduced percutaneously into the implanted device by inserting a needle into a port assembly of the device and delivering a fluid containing the therapeutic substance to the device via the needle.
Because the device is implanted within the patient and cannot be seen directly, care must be taken to ensure that the needle is properly placed into the port assembly before transferring liquids. If the needle is not located within the fill port assembly, delivery of the infusion media through the needle can result failure to adequately treat the patient and potentially dire consequences.
Accordingly, efforts have been made to identify to the clinician a location of the fill port assembly relative to the patient's skin prior to insertion of the needle. For example, templates are well known, and can provide a general indication or map of the port assembly location following palpating the device's periphery through the patient's skin. Additionally, electronic and/or magnetic systems have been suggested that provide the clinician with additional information generally indicative of the port assembly position. Regardless of how the clinician arrives at an initial estimation of port assembly location, upon inserting the needle through the patient's skin, the clinician normally must make a manual/tactile determination as to whether the needle tip has been correctly directed to the appropriate port assembly and has subsequently pierced through a septum covering the port assembly. Most clinician's are relatively comfortable in making this determination as, based on experience, the clinician can tactilely sense or feel when the needle has been inserted through the septum. However, it is sometimes difficult to know with certainty whether the septum has been accessed, especially with thick-skinned patients. Further, as implantable therapeutic substance devices become increasingly reduced in size, the attendant tactile feedback will diminish.
In light of the above, a need exists for a sensor capable of detecting needle presence in a port assembly of an implantable therapeutic substance delivery device. In addition, an indicator device for providing the clinician with a confirmation of desired needle positioning relative to the fill port may be desirable.